British Patent Application No. 2105520A discloses an electro-mechanical aircraft de-icer in which an electrical coil induces electro-magnetic impulses within a metal plate secured through a compliant spacing layer to the surface to be de-iced. The de-icer requires the use of high voltages and high energy special purpose capacitors and components such as thyristors and diodes which operate at the necessary high voltage and handle large currents for short periods. The high voltage brings difficulties with electrical insulation, weight and space requirements. None of this is desirable in aircraft, and one object of the present invention is to employ, for de-icing, voltages which are lower than those previously proposed.
British Patent Specifications Nos. 1222151 and 1369350 are earlier publications which, in common with 2105520A, proposed to induce electro-magnetic impulses within the sheath or skin of an aircraft. They therefore suffer from the same disadvantages.